Much of the enthusiasm for XLF and other bank ETFs is tied to the notion that a December rate hike by the Federal Reserve is, at this juncture, all but a foregone conclusion.

With a steepening yield curve, or wider spread between short- and long-term Treasuries, banks could experience improved net interest margins or improved profitability as the firms borrow short and lend long.

Heading into this year, many market observers expected four Fed rate hikes, a number that subsequently dropped to two and now, in the eyes of some experts, zero. Higher interest rates would help widen the difference between what banks charge on loans and pay on deposits, which would boost earnings for the financial sector.

There is another important catalyst to consider for financial services stocks and ETFs: The potential for bullish earnings trends to emerge.

Keefe, Bruyette & Woods analysts “write that they expect although estimates haven’t moved much yet, analysts should begin to move their models higher in the next two or three weeks to account for higher interest rates and potentially less regulation,” reports Teresa Rivas for Barron’s.